The proposed project seeks to add a neurocognitive component to a currently funded intervention trial for HIV medication adherence in methamphetamine using participants (1R01DA023395). In neuropsychological research, a link has been made between substance use and neurocognitive dysfunction, and in behavioral research, a link has been made between cognitive dysfunction leading to HIV risk behaviors. However, little if any research has been conducted to bridge the gap between neuropsychological and behavioral research. The management of HIV infection and the control of further transmission require HIV+ individuals to exhibit behavioral control in several domains, including the maintenance of near perfect adherence. Methamphetamine is known as a barrier to adherence, so addressing methamphetamine use is imperative in treatments for adherence in methamphetamine users. This study aims to address this gap between the neuropsychological and behavioral literatures by examining neuropsychological function in participants who have less than 90% adherence and use methamphetamine in order to;(1) study the effect cognitive factors have on risk-taking behaviors, (2) explore the reciprocal effects of substance use and medication adherence on cognitive performance, (3) examine the longitudinal cognitive deficits related to HIV infection, and (4) examine cognitive function as it relates to successful treatment for medication adherence and substance use. Participants will complete eight neurocognitive tasks relating to executive function (decision-making, impulsivity, cognitive flexibility), working memory and motor function at three time points, baseline and 3-month and 12-month follow ups. The public health impact of this project is twofold. First, with the insight provided by examining neurocognitive function in risk taking individuals, treatments could be developed that are more tailored to the individual needs of specific substance abusing and HIV-positive populations. Secondly, the study will provide the health field with information regarding the longitudinal changes in neurocognitive function caused by HIV infection, allowing for possible earlier diagnosis and treatment of HIV-associated dementia and HIV-associated Mild Cognitive Motor Disorder.